1. Field of the Invention
The present invention relates to an information processing apparatus for reproducing information from a disk-shaped optical information recording medium having a center portion, by receiving the medium and projecting a light beam on the medium.
2. Description of the Related Art
In an information processing apparatus, e.g., an optical disk apparatus, a cartridge which contains an optical disk, for use as a recording medium, is horizontally inserted into the apparatus through a loading aperture, and is held in a cartridge holder. When the cartridge is fed into a predetermined position in the cartridge holder, the holder descends. As the holder descends in this manner, the optical disk in the cartridge is mounted on a spindle motor, and an information recording surface of the disk is brought close to an optical head.
The spindle motor includes a turntable for positioning the optical disk with respect to the axial direction thereof, a spindle mounted on the central portion of the turntable and defining the center of rotation of the disk, and a motor section for rotating the spindle and the turntable.
The spindle is fitted in a center hole of the optical disk, thereby centering the disk securely. To this end, the tip portion of the spindle is tapered so that it can be easily aligned with the center hole of the optical disk, and projects above the upper surface of the turntable. In general, the optical disk has a hub with a predetermined thickness which defines the center hole. In consideration of the thickness of the hub, the tip portion of the spindle should project long enough above the upper surface of the turntable.
If the spindle for positioning the center of rotation of the optical disk always projects above the turntable surface in this manner, however, a relatively long distance must be secured between the loading path of the cartridge and the turntable surface in order to avoid a collision between the cartridge and the spindle tip when the cartridge is inserted or ejected in the horizontal direction, that is, in the direction parallel to the turntable surface along the loading path. Accordingly, the profile of the whole apparatus cannot be thinned with ease.
The same problem lies on an information processing apparatus of a type such that the optical disk or the recording medium is received directly without being contained in the cartridge.